This study is to examine whether high dose methylprednisolone has an effect on glucose and insulin metabolism as well as 1,25(OH)2 D3 in patients with nephrotic syndrome. Glucose tolerance will be measured by oral glucose tolerance tests. Insulin secretion will be measured by the hyperglycemic clamp method and 1,25(OH)2 D3 will be measured by immunoradiometric assay after preliminary charcoal extraction.